Re: [Xen-devel] [PATCH V1 17/29] xen/arm: Mark each device used by Xen as disabled in DOM0 FDT

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 09/09/2013 12:37 PM, Ian Campbell wrote:
> On Wed, 2013-08-28 at 15:47 +0100, Julien Grall wrote:
> > When a device has a property status with disabled inside, Linux will not use
> > the device.
> Do we not filter such devices out already?
We only filter gic/timer node. All the others nodes used by Xen, for 
instance the serial device, will be marked by status = "disabled".
> Or did the previous patch remove that functionality? In which case is
> there a bisection hazard here?
AFAIK, there is no bisection hazard with the current order of this patch 
series.
> Why is it preferred to leave the device with disabled in it instead of
> removing it? (Can this go in the changelog please)
> I think I've asked before, but is the handling of status = disabled
> generic and therefore reliable?
I let this patch because I didn't implement all the fake nodes in the 
previous patch series. In another hand, I'm not sure how Linux will 
react if there is a missing node and it should cope with status = 
"disabled" with most of nodes.
I will give a try and see if I can remove completely nodes used by Xen. 
Except, of course, gic and timer nodes which are recreated later.
> > Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> > ---
> >   xen/arch/arm/domain_build.c |    8 ++++++++
> >   1 file changed, 8 insertions(+)
> >
> > diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> > index 76decf4..d56bc70a 100644
> > --- a/xen/arch/arm/domain_build.c
> > +++ b/xen/arch/arm/domain_build.c
> > @@ -208,6 +208,14 @@ static int write_properties(struct domain *d, struct 
> > kernel_info *kinfo,
> >               return res;
> >       }
> >
> > +    /* Disable all devices used by Xen */
> > +    if ( dt_device_used_by(np) == DOMID_XEN )
> > +    {
> > +        res = fdt_property(kinfo->fdt, "status", "disabled", 8 + 1);
> > +        if ( res )
> > +            return res;
> > +    }
> > +
> >       /*
> >        * XXX should populate /chosen/linux,initrd-{start,end} here if we
> >        * have module[2]

--
Julien Grall

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